DescriptionEpipedobates machalilla is a slender frog with snout-vent lengths of 14.4 - 16.0 mm in males and 15.0 – 17.6 mm in females. The snout appears rounded in dorsal view and protruded in profile view. Their head is slightly longer than wide. The nostrils protrude slightly laterally. The tympanum is small and hardly visible. The forelimbs are moderately long with unwebbed fingers. Finger I is longer than finger II, with fringe absent on Finger II. The terminal discs of the fingers appear slightly expanded. The hind limbs appear long and moderately robust. The webbing is vestigial between Toes III and Toes IV. The toes lack lateral fringes and its terminal discs are slightly expanded. The dorsal and ventral surfaces are smooth (Coloma 1995).

Epipedobates machalilla can be distinguished from other species in the genus by its dark coffee-color and its non-venomous nature. Epipedobates machallila appears similar to Hyloxalus breviquartus, H. cevallosi, and Colostethuys fugax, and in that they all have solid, oblique lateral stripes, unmarked bellues, and rudimentary or absent membranes between the digits on the foot. However, E. machallila differs from C. fugax in that it is slightly larger and has an X-shaped mark on the scapular region. Epipedobates machalilla also differs from H. breviquartus and H. cevallosi in that the males have a swollen third digit on the foot (Coloma 1995).

In life, Epipedobates machalilla appears pale olive-tan on its dorsal surfaces, and have a dark brown X marking on the scapular region. The flank is dark brown to black. The upper lip is creamy yellow with pinkish shades. The oblique lateral strip is either creamy yellow or white with pale pinkish permeations projected anteriorly. The arms are pale orange and the dorsal surfaces of the legs are pale brown. The posterior surfaces of the thighs are yellowish orange. There is a discrete orange mark in the groin region. The ventral surfaces are cream color. The iris is gold color (Coloma 1995).

In preservative, the dorsal surfaces appear gray with dark brown marks. The oblique lateral strip is white. Black bands that extend from the tip of the snout to groin appear on the flanks. The upper lip is white. Two white stripes can be seen on the thighs. The posterior surface of the thigh is brown, decorated with small white spots. Transverse brown bars are present on the dorsal surfaces of the fingers (Coloma 1995).

There is significant geographic variation; with some specimens presenting with a narrow middorsal black stripe and in some specimens the white ventrolateral strip is indistinct. Other variants include individuals with small, scattered marks on the throat and individuals with two spots in the mental region (Coloma 1995).

Epipedobates machalilla can be found in dry and low areas of forests in west Ecuador, particularly in the provinces of El Oro, Los Rios, Bolivar, Guayas, Azogues, and Manabi. The species has also been observed in dry scrublands and deciduous forest in the coastal region, the Choco tropical rainforest, and forests in the western foothills. It has an altitudinal range of 10 - 515 m. It has also been found in disturbed habitats such as banana and cocoa plantations.

The species has also been observed to live in sympatry with Hyloxalus awa in the Mache Chindul moutains within the Cordillera de la Costa range and with Hyloxalus infraguttatus in the Chimbo River basin and Chongon Colonche range (Coloma 1995; CITES 2013).

Life History, Abundance, Activity, and Special BehaviorsEpipedobates machalilla has an elaborate mating system that incudes cephalic amplexus, and which usually takes place on ground. An average of 15 eggs, measuring 1.6 mm, are deposited on the ground or under dry leaves. After the amplexus, the female leaves and parental care is provided by the male, who carries the larvae and protects the development of the embryos from intruders by displaying aggressive behavior. (Coloma 1995; Del Pino et al. 2004) Once the tadpoles are hatched, after roughly 19 - 20 days from fertilization, the male carries the tadpoles into small pools or riverbanks where growth and metamorphosis takes place (CITES 2013).

In comparison to those of the Dendrobates genus, the eggs of E. machalilla are the smallest and least pigmented (CITES 2013).

Trends and ThreatsAccording to IUCN Global Amphibian Assessment documented in 2004, the population of E. machalilla is declining and is classified as “Near Threatened” because the population has reduced more than 30% over 10 years through significant loss of habitat across its range. The species is also a candidate to be listed as “Vulnerable” on the IUCN Red List of Threatened SpeciesTM (Coloma et al 2004).

The main, direct threat to E. machalilla is habitat deforestation in Ecuador due to expansion of agriculture (crops, livestock), logging, exploration and exploitation of non-renewable resources, construction of new roads, and installations of hydroelectric plants and dams (Coloma et al. 2004). It is speculated that 95% of the coastal forests have been degraded because of these types of agricultural conversions and urbanization. Some of the indirect threats to E. machalilla include temperature changes and the blooming human population in Ecuador. Because of the growing human population, there is more demand for goods and services that use the Ecuador’s natural resources, which is also shared with E. machalilla (CITES 2013).

Because of the threats to E. machalillia, it is included in the Strategic Plan for the Conservation of Amphibians in Ecuador (Coloma 2011). The species can be found in the public protected areas of Machalilla National Park and in the private protected areas of Cerro Blanco Protected Forest (Coloma et al. 2004).

CommentsWhen E. machalilla was first described in 1995, it was included in the Colostehus genus. Taxonomic revisions in 2006 then included the machalilla species in the Epipedobates genus (Coloma 1995).

The subspecies name machalill refers to the Machalilla National Park in which it is found (Coloma 1995).

E. machalilla is used for embryonic development studies (CITES 2013).

References

CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). Accessed April 2013 from http://www.cites.org/eng/cop/16/prop/E-CoP16-Prop-39.pdf